(1) Field of the Invention
The present invention relates to a novel method and device for measuring longitudinal and shear wave speeds in materials and, more particularly, to a novel method and device for measuring longitudinal and shear wave speeds in materials when they are under load.
(2) Background of the Invention
Ultrasonic testing is a widely used method for investigating the properties of various materials. In the standard test method, separate longitudinal and shear transducers are used to measure the longitudinal and the shear wave speeds in a material. This device is unique because it only requires a pair of shear transducers to achieve the same measurements. The wave speed measurements are done either using the transducers in transmission mode or in echo mode. Both wave speeds are necessary to determine the first order elastic constants of a material. Ultrasonic testing is the most sophisticated and widely used tool for characterizing elastic properties of crystalline materials. However, the characterization of foam-like materials, especially when the materials are subjected to a compression load, using ultrasonic testing presents new challenges due to the high attenuation of ultrasound within these materials. This invention specifically addresses these issues making the in situ ultrasonic testing of foams and other cellular materials possible.
What is needed in the art is a device that measures the mechanical properties of materials that are being deformed and damaged, protects the transducers from damage, allows for ultrasonic testing of a material under a compression load, and facilitates the interchanging of test samples. In addition, a continuing need exists for a method that allows one to fully characterize the mechanical properties of a material without using multiple transducers. The aforementioned needs are novel features of the present invention.